Light controlled electronic matrix switch



Aug. 17, 1965 c. v. PARKER LIGHT CONTROLLED ELECTRONIC MATRIX SWITCH Filed NOV. 50. 1961 m my m 6 xxxx xg LEE INVENTOB CARLYLE V. PARKER ATTORNEY? United States Patent 3,291,764 LIGHT CONTROLLED ELECTRONIC MATRIX SWITCH Carlyle V. Parker, Alexandria, Va., assignor to the United States of America as represented by the Secretary of the Navy I Filed Nov. 30, 1961, Ser. No. 157,046 7 Claims. (Cl. 340173) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates generally to an improvement in matrix switching and more particularly to an all electronic light-controlled matrix network which provides permutation changes as the radix is changed to binary.

He'retofore, it was customary to employ permutation circuits with an output radix that was the same as the input radix and when it was desired to switch from one code system to another, such as decimal to binary, a separate radix changing'circuit was required. Prior circuits that attempted to alleviate this situation were limited in the number of matrixcombinations possible. In the application of C. J'. Creveling, Serial No. 771,167, filed on October 31, 1958, also assigned to the Government of the United States and now abandoned, a unique system of combining these two features in one network operation and providing a maximum number of combinations is more fully described.

Generally in the aforementioned application for a matrix'network as well as in other conventional selective signal networks, the selection of a desired signal is effected by mechanical (metal to metal) contacts and while such networks have been found practical for certain applications, the extent of their utilization is limited, especially when such networks are confronted with the rigid requirements of space and satellite apparatus. Networks employing mechanical contacts are bulky, consume precious weight, become unreliable due to uneven wear, are subject to variable spring tension or friction causing sticking of contacts and become highly susceptive to temperature variations causing varying contact pressure due to unequal expansion or contraction. Then when mechanical contacts are employed the response and operating time of such prior networks has been limited by the delay in setting and resetting the respective switch junctures.

Accordingly it is an object of this invention to provide an improved electronic selecting matrix while providing the operation of permutation and the operation of radix changing in a single circuit.

It is also an object of this invention to improve the reliability and switching speed of a selective signal network which is capable of performing permutation and radix changing in the same operation, in the same circuit.

It is a further feature of this invention that light controlled semiconductive elements be connected at each juncture or crossover point in the selective signal matrix network.

It is also a feature of this invention to utilize a light controlled bistable switching combination for providing an all electronic matrix network yet capable of providing the permutation and radix change operations in a single circuit.

The general purpose of this invention is to provide a selective signal network that will provide a permutation and radix change in a single operation in a single matrix without the use of mechanical (metal-to-metal) contacts for making connections, with complete freedom of choice in making the connection, to permit all the connections to be made simultaneously and to be broken simultaneously 32%,764 Patented Aug. 17, 1965 "ice by a single action and to retain the plurality of connections indefinitely, through a-memory of initial conditions regardless of the state of the initiating means.

Other objects, features and purposes of this invention will become apparent to those skilled in the art as the disclosure is made in the following detailed description and accompanying drawings in which:

FIG. 1 is a partially schematic and partially block diagram of a matrix network; and

FIG. 2 is a schematic diagram of a light controlled bistable switching circuit employing a photo-diode and a four layer semiconductor in accordance with the principles of this invention.

Referring now to the drawings, wherein like reference numerals designate the same parts throughout the several figures, FIG. 1 shows an embodiment of a multipleconnection switch network without mechanical contacts yet capable of performing both a radix change and permutation in the same operation, in the same circuit. As more fully explained in the aforementioned patent application, the matrix consists of several input conductors and several output conductors such as might be used in converting from a decimal numbering system to a binary numbering system. By connecting a unidirectional element and a switching element in combination between each input and output conductor the matrix can permute as well as change its binary in a single network. In a decimal to binary conversion, if the combination is set for a radix change without permutation, a pulse applied to a particular input conductor will produce an output pulse group at the output conductors which define that particular input terminal in a binary form. Now by selectively altering the switch setting, the decimal to binary conversion can be maintained but a permutation can also be performed. It should be appreciated that with the number of input conductors provided, the maximum number of permutations possible can be performed and still a conversion to binary form is always present.

In FIG. 1, a matrix 11 is shown comprising a plurality of input conductors 12 to 21 in one coordinate, a plurality of output conductors 22 to 25 in another coordinate and a plurality of ligh sensitive bistable switching elements capable of remembering their present state, interconnecting each input conductor with each output conductor, such as shown at juncture 26 to 30. Providing energy for actuating the light sensitive switching junctures is a source of light source 31 whose energy can be programed by a coded card 32 thereby providing for a predetermined switching combination. A control lead 45 is also employed for resetting each switching juncture to its initial condition after the juncture has been actuated by energy from light source 31.

While only ten input conductors have been shown in FIG. 1 it should be appreciated that any number can be used and with the network as shown, up to sixteen input conductors can be used with the four output conductors, with the same advantages as with ten conductors. If only eight input conductors are to be used then only three output conductors are required.

To provide a switching juncture for interconnecting the input conductors 12 to 21 to the output conductor 22 to 25, that would overcome the limitations imposed by mechanical contacts and still perform as required, it was found necessary that the switching elements must have the property of a grid-controlled thyratron tube of staying off until the control electrode is biased forward and thereafter continuing to conduct regardless of the control potential until the anode to cathode circuit is interrupted. Such a switching juncture for the matrix of FIG. 1 is shown in FIG. 2. Here, the switching juncture 26 comprises a four-layer diode 33 consisting of four alternating '3 layers of P-type and N-type semiconductor material. The tour-layer diode 33 is biased by a power supply 34 through current limiting resistor 35 so that the two emitter-base junctions 37 and 38 are forward biased while the collectorbase junction 39 is reverse biased. The voltage from power supply 34 must be less than the breakdown voltage for diode 33. A control gate lead 40 is coupled to the layer of semiconductor material that forms the collectorbase junction and coupled through resistor 41 to a photosensitive diode 42, which is biased by a power supply 4-3. Of course it should be understood that the power supplies 3% and 43 may be one unit having only different tapping leads for the respective diodes. Light energy for controlling the movement of carriers in the photo-sensitive diode 42 is provided by source 31 while the light energy allowed to fall on the sensitive p-n junction of diode 42 is programmed by coded card 32. When the light energy from source 31 is allowed to strike the p-n junction of diode 42 the current flow through diode 42 increases. This increase of current is used to trigger the four layer diode by causing the control gate lead 4% to inject current into the collector base region of the four-layer diode 33, lowering the breakdown voltage for the diode below the voltage impressed on the diode by power supply 34. Once the gate lead 40 has triggered the four-layer diode 33 into its low impedance, on state, it no longer has any control over the diode. Diode 33 will remain in this state re gardless of the condition of control gate lead 40 until the voltage impressed by power supply 34 is interrupted. Then diode 33 will return to its initial high impedance oil state. Thus a low impedance, current controlled switch having similar characteristics as a high impedance, voltage controlled gas thyratron switch but without the latters limitations is provided for the switch juncture between the input conductors 12 to 21 and output conductors 22 to 25.

In operation, the choice of a code'for actuating the matrix network ll is made by programming an opaque card 32, inserting the card betwen the light source 31 and the matrix 11, and turning the light source 31 on momentarily. Wherever openings have been programmed on the card, the switch junctures associated with the opening will be triggered on due to momentary illumination of the photosensitive diode whereas the switch junctures associated with no openings in the card 32 will be maintained in their initial state due to the bias by power supply 34 in Fl G. 2. The light can be turned off and the program card 32 removed without affecting the on-otl state of the respective switch junctures.

It now a decimal number is chosen by applying a potential difference to one of the input conductors 12 to 21, as for example by a positive pulse, then a potential difference will appear on one or more of the four output conductors, thus giving its binary equivalent according to whichever coding system was represented by the program card 32.

To choose a different coding system the power supply 34 must be momentarily interrupted, such as by control conductor 45 so as to reset all the switched junctures back to their initial open or off condition. A new program card is then inserted between the light source 31 and matrix network 11, and the light source turned on. Again the switch junctures that are associated with an opening in the program card will be switched into a closed or on state. The program card may be Withdrawn if desired. In actual operation there will be only one power supply for all switching junctures and only one control conductor needed to interrupt the power supply in order to reset all four-layer diodes to the high impedance state. A preferable embodiment of this invention when space and weight must be kept to a minimum is to combine the four-layer diode and photo-diode into a single element which would perform the same function except that the four-layer device would be triggered directly by light falling on the collector-base junction of the four-layer semiconductor. It is also possible to construct the switch by depositing the semiconductor material in the form of a rectangular matrix on etched-wiring board and in this way long leads uch as shown in the respective figures could be avoided and a large number of contacts obtained in an extremely small region.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In a light-sensitive electronic matrix system capable of performing both a permutation and radix change simultaneously, the network combination of, a plurality of input conductors, a plurality of output conductors representing a binary radix, said plurality of output conductors being sufficient to represent in binary form the number of input conductors individual switching means connecting each input conductor to each output conductor, said switching means comprising a photo-sensitive semiconductor in controlling connection to a bistable semiconductor, a source of energy for actuating said photosensitive semiconductor, means to program the permutation and radix change by controlling which photo-sensitive semiconductor will be actuated by said source of energy, and means for resetting said bistable semiconductor.

2. A light-sensitive electronic matrix system as set forth in claim 1 wherein said bistable semiconductor comprises a four-layer diode wherein one intermediate junction is controlled and caused to trigger by energy received from said photo-sensitive semiconductor.

3. An all electronic light-controlled matrix network which provides permutation changes as the radix is changed to binary, the combination of: a plurality of input conductors; a plurality of out-put conductors representing a binary radix, the number of said output conductors being sufiicient to represent in binary form the number of input conductors; a four-layer diode connecting each input conductor to each output conductor, said four-layer diodes having a control lead and alternate layers of P-type and N-type semiconductor material and being normally biased into a high impedance, nonconducting state; a photo-sensitive diode connected to the control lead of each of said four-layer diodes and being effective, when energized, to change said four-layer diodes into a low impedance, conducting state; a light source; a coded, punched card placed between the light source and all of the photo-sensitive diodes and masking all but selected ones of said photosensitive diodes from said light source, whereby said selected ones of said photo-sensitive diodes are energized by said light source to change the four-layer diodes connected to each of said selected diodes to the low impedance, conducting state and thereby provide the desired permutation in the radix changing matrix network.

4. An an electronic light-controlled matrix network as set forth in claim 3 wherein each four-layer diode is connected to means for restoring said four-layer diode to its initial high impedance, nonconducting state.

5. In a light sensitive selective signal circuit network capable of performing both permutation and a radix change in the same circuit, comprising a plurality of mput conductors, a plurality of output conductors, said output conductors limited to a number suflicient to provide a binary output representation of said input conductors, a plurality of light sensitive bistable switching elements connecting each input conductor to each output conductor, said bistable switching elements being capable of remembering their present state regardless of whether or not light energy is available, a source of light energy, means for programming the permutation and radix change by controlling said light energy, said light sensitive bistable switching device composed of a multilayer semiconductor having several -p-n junctions wherein one p-n junction is controlled by said light energy and the multilayer semiconductor is switched into a conducting state when said control junction is triggered by said light energy.

6. In the selective signal circuit network as set forth in claim 5 wherein said multilayer semiconductor comprises a four-layer diode of alternating layers of P type and N type material forming several intermediate junctions, a control lead connected to one of said intermediate junctions, means biasing said four-layer diode into a high impedance nonconduc-ti-ng state, a photo-sensitive p-n semiconductor diode operatively associated with said programming means and said light energy sou-rec, said photosensitive diode being connected to said control lead whereby said intermediate junction is activated when said photo-sensitive diode is triggered by light energy.

7. In the selective signal circuit network as set forth in claim 6 wherein means for resetting said four-layer diode into a high impedance nonconducting state are connected to said biasing means.

References Cited by the Examiner UNITED STATES PATENTS 1,072,152 9/13 Oca-rnpo 23561.l15

2,727,685 12/55 Wilson 235-152 2,838,617 6/58 Tommers 30788.5 2,909,973 10/59 Koelsch et a1. 340-173 OTHER REFERENCES Page 38, June 195 8, IBM Technical Disclosure Bulletin, volume 1, No. 1.

Page 1, December 1958, IBM Technical Disclosure Bulletin, volume 1, No. 4.

Page 85, February 1960, IBM Technical Disclosure Bulletin, volume 2, No. 5.

Pages 4l0, September 1960, Applications and Circuit Design Notes, Bulletin D420-02-0-60 by Solid State Products, Inc., Salem, Mass.

Page 57, October 1960, IBM Technical Disclosure Bulletin, volume 3, No. 5.

Page 36, December 1960, IBM Technical Disclosure Bulletin, volume 3, No. 7.

20 IRVING L. SRAGOW, Primary Examiner. 

1. IN A LIGHT-SENSITIVE ELECTRONIC MATRIX SYSTEM CAPABLE OF PERFORMING BOTH A PERMUTATION AND RADIX CHANGE SIMULTANEOUSLY, THE NETWORK COMBINATION OF, A PLURALITY OF INPUT CONDUCTORS, A PLURITY OF OUTPUT CONDUCTORS REPRESENTING A BINARY RADIX, SAID PLURALITY OF OUTPUT CONDUCTORS BEING SUFFICIENT TO REPRESENT IN BINARY FORM THE NUMBER OF INPUT CONDUCTORS, INDIVIDUAL SWITCHING MEANS CONNECTING EACH INPUT CONDUCTOR TO EACH OUTPUT CONDUCTOR, SAID SWITCHING MEANS COMPRISINGA PHOT-SENSITVIE SEMICONDUCTOR IN CONTROLLING CONNECTION TO A BISTABLE SEMICONDUCTOR, A SOURCE OF ENERGY FOR ACTUATING SAID PHOTOSENSITIVE SEMICONDUCTOR, MEANS TO PROGRAM THE PERMUTATION AND RADIX CHANGE BY CONTROLLING WHICH PHOTO-SENSITIVE SEMICONDUCTOR WILL BE ACTUATED BY SAID SOURCE OF ENERGY, AND MEANS FOR RESETTING SAID BISTABLE SEMICONDUCTOR. 